Selective pressure cooling for engines



' March 28, 1939. A.'T GREGORY 2,152,043

SELECTIVE PRESSURE COOLING FOR ENGINES Filed Jan/50, 1937 2 Sheets-Sheet l 1 ATTORNEYS March 28, 1939. A. T. GREGORY SELECTIVE PRESSURE COOLING non mamas 2 Sheets-Sheet 2 Filed Jan. 50, 1957 INVENTOR flZ/rzdf lirgg ary Patented Mar. 28, 1939 -UNlTlID STATES PATENT OFFICE I smnc'rrvn rn rEi-zlcoomc For. I

Alfred T. Gregory, Fa'rmingdale, N. Y., assignor to Ranger Engineering Corporation, g-

10 Claims.

This invention relates to a selective air cooling system for internal combustion engines and has particular reference to a system of air-jacketing the cylinders of aeronautical engines in which air under pressure enters the jackets at selected points at high velocity, flows around the cylinders in desired directions and leaves the jackets again at selected points at a high rate of flow.

Heretofore it has been the practice to collect a portion ofthe air blast induced by the propeller oraby the movement of the aeroplane through the airand direct it by means of suitable cowling upon the walls of the cylinders, which are provided with the usual heat-radiating fins. With this general arrangement the cooling air is distributed over the engine substantially uniformly in radial type engines but not particularly uniformly in engines in which the cylinders are arranged in line. The forward and rear cylinders in the in-line type of engine, therefore, are not equally effectively cooled. Furthermore, the distribution of the cooling air over the surface of the individual cylinders with this general arrangement is substantially uniform in all engines without regard to the unequal heating of the various portions of the cylinders. Thus, those portions of the cylinder heads around the spark plugs, which operate at considerably higher temperatures, say than the cylinder barrels, are not cooled particularly more efiectively than the barrels. 0n thetheory that to obtain maximum cooling efliciency with a given weight of cooling air it is essential to cool the various parts of the cylinder head to a substantially uniform temper- 85 ature, and that simultaneously the cylinder barrel temperatures should also be uniform at as high a value as permissible, the present invention is designed to accomplish these ends.

In accordance with the present invention, a

40 selective air pressure cooling system, particularly adapted for aeronautical engines, is provided, in which a plate extends along a rowof the engine cylinders and forms a wall of a substantially closed chamber having an opening for receiving 45 a portion of the high velocity propeller or slip air stream, which builds up a substantial static pressure in the chamber by reason of its velocity and the air-trapping action of the chamber. The plate is provided with confined openings or slits 50 of substantially less total area than that of the air intake opening of the chamber, through which the air from the chamber is allowed to flow at high velocity and substantial pressure so as to be directed upon selectedparts of the cylinders- 55 around which the air then flows turbulently to exh'aust of the spent cooling air from the cowl by the opposite side, preferably for further direction through an apertured second plate positioned along the rear of the cylinders. The apertures in the second plate are likewise so positioned that aspiration. The invention is equally adaptable to multi-row cylinder engines, such as those of the V type in which the plates are arranged in the manner described along opposite sides of each row of cylinders, and one of them forms a wall of an air stream trapping chamber in which the air builds up a substantialstatic pressure in the manner described.

It will be seen that with the selective air pressure cooling system of this invention, the cooling air is initially blocked oil so as to be trapped and builds up a substantial static pressure, is then admitted to the cylinders at high velocity only at points requiring the most efiective cooling, is metered to the various points on the cylinders in order to equalize the cooling of the difierent c'ylinders throughout the engine, and otherwise provides an air jacket cooling system for the engine so designed as to direct the flow of cooling air over the cylinders in any desirable way, whereby the air is not only wrapped around the cylinders in the direction of their fins but is also caused to have a turbulent flow across the fins and is then led to discharge points requiring the greatest volume and velocity of cooling air, so as to obtain the most effective cooling.

For a more complete understanding of the invention, reference may be had to the accompanying drawings, in which:

Figure 1 is a front perspective of an inverted, in-line aeronautical engine having a single row of cylinders provided with the selective air cooling system of this invention;

Fig. 2 is a horizontal section therethrough in the plane of the spark plugs, as seen along the line 22 of Fig. 1, and illustrates the arrangement of the air jacketing for the cylinders together with the air scoop and engine cowling;

Fig. 3 is a face view of a portion of the jacket plate as seen along the line 3-3 of Fig. 2 with the air scoop removed;

Fig. 4 is a face view of a portion of the rear baiile arrangement asseen along the line 4-4 of Fig. 2; and

Fig. illustrates the invention as applied to a V engine.

Referring to Fig. 1 of the drawings, numeral i designates a six-cylinder inverted in-line aeronautical engine. The camshaft housing is indicated at 2, and-each cylinder is provided with an exhaust pipe 3. The cylinders are provided with suitable parallel radiating fins in accordance with the usual practice. The main crankcase, to which the cylinders are secured, is shown at 4.

A sheet metal air scoop 5 extends from the main crankcase 4 to the camshaft housing 2 and is preferably secured thereto. The scoop opening is directed in the direction of movement of the aeroplane, so as to receive aportion of the air stream produced by the propeller thrust, or caused by the movement of the aeroplane through the air, or both. This scoop 5 is closed along the top and bottom and at the rear of the engine by an inward extension 5 to the cylinder bank, as illustrated in Fig. 2.

Extending closely along the row of cylinders is a jacket plate 6, which is suitably secured at its lower edge to the cylinders, and at its upper edge to the crankcase 4. The jacket plate 6 is accordingly positioned as shown in Figs. 1 and 3 along the row of cylinders and, except for certain air ports therein, to be described, assists the scoop 5 to form a substantially closed chamber l in which the trapped air builds up a considerable static pressure as the aeroplane moves through the air, the degree of pressure depending upon the velocity of movement of the airplane, the rotational speed of the propeller, or, if an auxiliary blower is used, on the capacity of the blower, and on the relation in size between the entrance opening to the scoop 5 and the total area of the ports in the jacket plate 6.

As shown in Figs. 2 and- 3, the jacket plate 6 is provided with ports 8 through which the spark plugs 9 project and through which a portion of the pressure air flows from chamber 1 and impinges at high velocity against the spark plugs and a portion of the cylinder walls.

In order to cool the cylinder barrels more effectively, long narrow slots, ii, may be provided in the jacket plate opposite the center of each cylinder. A column of relatively cold air thus impinges at high velocity against the cylinder barrel surfaces after which the air flows around the cylinder between and around the cooling fins to the rear. The total area of the jacket plate ports 8, the slots ii, and any other openings, is less than the air intake opening of the scoop 5, so that the aforementioned static pressure in chamber 1 is maintained at all times during operaticn of the airplane or propeller thereof.

The inter-cylinder space is provided with outer bailles l2, shown in Figs. 2 and 4, which are of such shape as to cause the air stream to wrap itself around the cylinders and also to cause it to flow at high velocity over the highly heated portions of the engine before exhausting out of the jacket. This jacket consists of the plate 6, and the baflies i2, which substantially completely enclose the cylinder bank, as illustrated in Fig. 2.

It will be observed that the rear baiiies i 2 jointly form, in effect, a rear plate similar to front jacket plate 8, and if desired the baflles i2 may be joined into a single plate similar to plate 6, and vice versa. Air enters the system at the intake opening it of scoop 5 and is exhausted at I4. from the low pressure chamber l8 formed between the cowling l9, rear wall I8 and the rear baflles I2 and cylinder walls. The arrows in Fig. 2 indicate the general air flow. While the exhaust opening I4 is preferably located at the rear of the engine it may be located elsewhere as long ash is arranged to permit free exhaust of spent cooling air or to aspirate or draw the spent. air from the space l8.

In operation, the pressure air trapped in chamber I in the manner described is selectively distributed underv pressure through the ports and slots 8 and il in the jacket plate 6, i. e. around the spark plugs 9 and against selected portions of the cylinder walls, thence in a turbulent flow across the radiating fins and around the cylinders in the direction of their fins; through the spaces between the cylinder walls, fins and surfaces of the rear or outside bailies i2; through the openings l5 around the lee spark plugs ll; through the openings it between each pair of rear bafiles l2 into the low pressure space l8 inside the cowl I9, and exhausts through the rear opening i4. As illustrated in Fig. 2 the air exhaust opening I4 is louvre-shaped so that the high velocity slip stream flowing over the smooth outer surface of cowl l9 creates a suction through opening i4, thus withdrawing the spent cooling air by aspiration, which decreases the pressure within space l8 and thus increases the pressure head between chambers I and I8.

The cooling air, being continuously under pressure, has a large cooling capacity, has the same pressure at all cylinders to afiord uniform cooling along the entire cylinder bank, and is under constant control to provide metered, selective,

pressure cooling effects where'cooling is most required. For example, it will be observed that the air ports or slots 8 and II are not only located at points where the most cooling is needed, but are shaped to direct the air at high velocity over those points and are also proportioned in size to conform to the cooling that is necessary. Thus, the openings 8, at the cylinder heads are relatively large, since that is the hottest part of the cylinder and are shaped to direct the air axially in this case along the spark plugs 9 to the spark plug bosses, while the slots Ii are rela- 'tively smaller in area since the walls of the tioning of the air openings, the air is compelled to flow over the cylinders in whatever manner is desired.

Fig. 5 illustrates the invention as applied to an engine having two banks of cylinders 20 arranged in inverted V formation. The air scoop 2| spans the space between the cylinder banks and may be secured at its edges to the opposite cam shaft housings 22. The scoop 2| is closed at the rear as before and forms with the inner jacket plates 23 a closed chamber 24, except for the aforementioned spark plug ports and elongated cylinder jet slots. The high-velocity incoming air is trapped in chamber 24 and is maintained at high static presbaiiies 25 cooperate with the inner jacket plates 23" sure as described. The outer Jacket plates or to air jacket the cylinders 20. It will be understood that the front ends of the air Jackets formed by plates 23 and 25 for each bank of cylinders are shown removed in Fig. 5 in the interest of clearness. It will also be understood that the two or more rows of cylinders need not be arranged in V relation, but may also be in parallel planes or other relation.

In operation, in the arrangement of Fig. 5, air is trapped and compressed within chamber 2i,

due to the relative velocity of the entry air stream and the smaller gross area of the exit ports compared to the area of the scoopintake opening. This pressure air flows from chamber 24 through the reduced openings in the inner Jacket plates 23 to cool the parts in the manner-described in connection with the arrangement of Figs. 1 and 2, and then flows underpressure out of the openings in outer jacket plates 25, or between the bailies forming it, as the case may be. As with the arrangement of Figs. 1 and 2, there is a graded pressure difierential between the successive chambers as the air flows from the high pressure chamher to the next chamber.

I claim:

1. In an aeronautical engine having a plurality of cylinders arranged in a row, the combination of a plate extending along one side of the row of cylinders, and having a width substantially equal to the exposed height of the cylinders of the engine, and an air scoop directed in the direction of travel of the engine and cooperating with said plate to form a substantially closed chamber for trapping a portion of the air stream under pressure, said plate having restricted openings for directing pressure air at relatively high velocity from said chamber upon predetermined portions of the cylinders of the'engine.

2. In an aeronautical engine having a plurality of cylinders arranged in a row, the combination.

of a plate extending along' one side of the row of. cylinders, and extending laterally from the bases substantially to the top of the heads of said cylinders, bafiles between the heads of the cylinders, and an air scoop directed in the direction of travel of the engine and cooperating with said plate,

' cylinder head walls and said baffles to form a subof cylinders arranged in a row, the combination of a plate extending along one side of the row of cylinders, and an air scoop directed in the direction of travel of the engine and cooperating with said plate to form a substantially closed chamber for trapping a portion of the air stream under pressure, said plate providing relatively large openings adjacent the heads of the cylinders and relatively smaller openings adjacent the cylinder walls for the passage of pressure air from said chamber.

4. In an aeronautical engine having a plurality of spark plug fired cylinders arranged in a row, the combination of a plate extending along one side of therow of cylinders, and an air scoop directed .in the direction of travel of the engine and cooperating with said plate to form a substantially closed chamber for trapping a portion of the air stream under pressure, said plate having restricted openings adiacent the spark plugs of the engine for directing pressure air from said chamber upon said spark plugs.

5. In an aeronautical engine having spaced cylinders and adapted to be located in an air stream, an air scoop substantially enclosing one side of said cylinders and having an opening for directing a portion of the air stream into said scoop, and means interposed between said scoop and said side of the cylinders for substantially blocking oii the latter from said scoop and forming therewith a substantially closed chamber, said means providing restricted passages, of less total area than the air scoop'opening, for directing air from said chamber on selected parts of the engine.

6. In an aeronautical engine having spaced cylinders and adapted tobe located in an air stream, an air scoop substantially enclosing one side of said cylinders and having an opening for directing a portion of the air'stream into said scoop, means interposed between said scoop and said side of the cylinders for substantially blocking of! the latter from said scoop and forming therewith a substantially closed chamber, said means providing restricted passages, of less total area than the air scoop opening, for directing air from said chamber on selected parts of the engine,

and a cowl substantiallyenclosing the opposite side of said cylinders and having an opening for exhausting the air flowing through said passages.

7. In an aeronautical engine having spaced cylinders and adapted to be located in an air stream, an air scoop substantially enclosing one side of said cylinders and having an opening for directing a portion of the air stream into said scoop, means interposed between said scoop and said side of the cylinders for substantially blocking off the latter from said scoop and forming therewith a substantially closed chamber, said means providing restricted passages, of less total area than the air scoop opening, for directing pressure air at relatively high velocity from said chamber on selected parts of the engine, a cowl substantially enclosing the opposite side of said cylinders, and means on the cowl cooperating with said air stream to reduce the pressure within said cowl by aspirating from the cowl the spent cooling air flowing through said passages.

8. In an aeronautical engine having at least two rows of cylinders arranged in spaced relation and adapted to be located in an air stream, the combination of a plate extending along the inner side of each row of cylinders, and an air scoop having an opening directed into the air stream and extending across the space between the rows of cylinders to form with the said plates a substantially closed chamber for trapping a portion of the air stream under pressure, said plates providing restricted openings for directing pressure air from said chamber upon predetermined portions of the cylinders.

9. In an aeronautical engine having at least two rows of cylinders arranged in spaced relation and adapted to be-located in an air stream, the combination of a plate extending along the inner side of each row of cylinders, an air scoop having an opening directed into the air stream and extending across the space between the rows of cylinders to form with the said plates a substantially closed chamber for trapping a portion of the air stream under pressure, and means extending along the outer side of each row of cylinders for substantially blocking the intercylinder spaces, said plates and means jointly forming an air jacket for each row of cylinders, said plates providing restricted openings for directing pressure air drom said chamber upon predetermined portionsioi' the cylinders, and said means providing discharge openings irom the corresponding air jacket for causing the air flowing through said Jacket to follow predetermined paths.

10. In an aeronautical. engine having at least two rows of cylinders angularly arranged about the crankshait thereof and adapted to be located in an air stream, the combination of an air scoop extending between said rows of cylinders from a point adjacent the heads thereof and substantial- 1y enclosing the space between said rows of cylinders, said scoop having an opening tor directin: a portion 01' the air stream into said space, and cans cooperating with each 0! said rows of cy ders and forming with said scoop a substantially closed chamber in which the air entering said scoop opening. builds up a substantial pressure, said means providing restricted passages of less total area than the said scoop opening ior directing pressure air at relatively high velocity 10 from said chamber on selected parts or the engine.

ALFRED T. GREGORY. 

